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July 23, 2011

Truck Maintenance Tip: Pre-set hub bearings

Weeping hub seals are a real nuisance. And if my experience is any indication, you're just as likely to find leaking seals on new trucks as on trucks in service for several hundred thousand miles. It just goes to show that installing and setting wheel seals and bearings requires skill. Careful handling of the seals and then precise setting of the hub bearings to minimum runout is a requirement.

Industry standards set by The Maintenance Council of the American Trucking Associations (ATA) says wheel bearing clearance should be 5/1000 of an inch or less. But even this small amount of runout is not as good as a slight bearing preload. The problem is you can't easily measure the preload.

To completely eliminate the problem, I'd recommend specifying the latest type of integrated wheel-ends with your next truck. These hubs feature spacers between the bearings to guarantee the settings regardless of the torque on the axle-end nuts. One design even ensures a positive oil circulation in and through the bearings for cooler running and longer bearing life.

Another bonus with the latest designs is the semi-sealed hubcap that allows for pressure relief with temperature change but which positively blocks water and dirt from getting into the bearing and oil.

Keeping out water and dirt, maintaining bearing clearance and alignment, and keeping wheelends cool is a sure recipe for long seal life - providing they have been installed correctly in the first place!

1 comment:

  1. One concern is that auto makers will produce much lighter cars in order to meet the CAFE regulations. Lighter cars are great for mpg but not so great in case of an accident.
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